In 3rd Generation Partnership Project (3GPP), in order to achieve high-speed and large-capacity communication between a radio communication base station apparatus (hereinafter, abbreviated as a “base station”) and a radio communication terminal apparatus (hereinafter, abbreviated as a “terminal”), Long Term Evolution (LTE) and LTE-Advanced have been standardized, and standardization for further enhancement has been in progress.
In LTE and LTE-Advanced, Orthogonal Frequency Division Multiple Access (OFDMA) has been employed as a downlink communication scheme, and Single Carrier Frequency Division Multiple Access (SC-FDMA) has been employed as an uplink communication scheme (see Non-Patent Literature (hereinafter, abbreviated as NPLs) 1, 2, and 3, for example).
The channels and signals used in uplink communication include a Physical Uplink Shared Channel (PUSCH), a Physical Uplink Control Channel (PUCCH), and a Sounding Reference Signal (SRS), and the like. The PUSCH is a channel by which data signals are transmitted. The PUCCH is a channel by which control information such as ACK/NACK information or CQI information is transmitted. The SRS is a reference signal used to measure a channel quality in a base station.
The base station allocates a resource block (RB) used to transmit the PUSCH and PUCCH to each terminal in units of subframes. Further, the base station sets a cycle, timing and bandwidth used to transmit the SRS. Note that, a subframe (1 ms) typically consists of 14 SC-FDMA symbols (71.3 μs) (hereinafter, abbreviated as “symbols”).
The terminal transmits the PUSCH and PUCCH using the RB and the subframe allocated by the base station. The terminal transmits the SRS using one symbol at the end of a subframe at the cycle, timing, and bandwidth set by the base station. The terminal transmits the PUSCH and PUCCH using 13 symbols excluding the symbol at the end in the subframe for transmitting the SRS.
The terminal controls transmission power of the PUSCH, PUCCH, and SRS in units of subframes.
Transmission power PPUSCH (i) [dBm] of the PUSCH is obtained by Equation 1 below. In Equation 1, “i” represents a subframe number, PCMAX,C(i) indicates permissible transmission power, MPUSCH(i) is a transmission bandwidth (the number of RBs) allocated to the PUSCH, P0_PUSCH is a transmission power offset value (a transmission power initial value of PUSCH) indicated by the base station, PL represents a path loss measured by the terminal, α represents a weighting coefficient (a value of 0 to 1) indicating a compensation ratio of a path loss indicated by the base station, ΔTF(i) is an offset value that depends on a modulation scheme or the like, and f(i) represents an offset value according to a TPC command indicated by the base station.
[1]PPUSCH(i)=min{PCMAX,10 log10(MPUSCH(i))+PO_PUSCH(j)+α(j)·PL+ΔTF(i)+f(i)}  (Equation 1)
Transmission power PPUCCH(i) [dBm] of the PUCCH is obtained by Equation 2 below. In Equation 2, P0_PUCCH represents a transmission power offset value (a transmission power initial value of the PUCCH) indicated by the base station, h(nCQI,nHARQ,nSR) represents an offset value that depends on information or a format transmitted through the PUCCH, ΔF_PUCCH(F) represents an offset value indicated by the base station, and g(i) represents an offset value according to a TPC command indicated by the base station.
[2]PPUCCH(i)=min{PCMAX,P0_PUCCH+PL+h(nCQI,nHARQ)+ΔF_PUCCH(F)+g(i)}  (Equation 2)
Transmission power PSRS(i)[dBm] of the SRS is obtained by Equation 3 below. In Equation 3, PSRS_OFFSET represents a transmission power offset value on the transmission power of the PUSCH indicated by the base station, and MSRS(i) represents a transmission bandwidth (the number of RBs) allocated to the SRS.
[3]PSRS(i)=min{PCMAX,PSRS_OFFSET+10 log10(MSRS(i))+PO_PUSCH+α·PL+f(i)}  (Equation 3)
LTE-Advanced Release 10 (hereinafter, abbreviated as a “Rel.10”) supports carrier aggregation (CA) in which a plurality of component carriers (hereinafter, abbreviated as “CCs”) each having a frequency bandwidth of a maximum of 20 MHz (that is, a maximum frequency bandwidth in LTE) as a basic unit are aggregated and operated. CA in Rel.1 does not support simultaneous transmission of PUCCH and SRS or PUSCH and SRS. For this reason, when setting or allocation for simultaneous transmission of PUSCH or PUCCH and SRS is indicated by the base station, the terminal does not transmit (drops) the SRS in a corresponding subframe.
Further, in Rel.10, when the sum of transmission power calculated by Equations 1 to 3 exceeds a permitted value for simultaneous transmission of PUCCH and PUSCH between CCs, power is preferentially allocated to the PUCCH, and power of the PUSCH is reduced. The permitted value of the transmission power of the terminal is maximum power supported by the terminal or permissible transmission power (a maximum value) indicated by the base station.